A 34-year-old Hispanic woman was admitted to the hospital with altered mental status and fever. The patient had been suffering from systemic lupus erythematosus for a number of years, with several small strokes that left her partially paralyzed on the left side. A urinary tract infection was diagnosed, and she was treated with antibiotics and steroids with good results until she aspirated, developed pneumonia, and became comatose. After an intensive care unit stay of several weeks, she emerged from her coma. She was noted to have frequent crying spells. A psychiatric consultation was requested.

The consultant diagnosed a depressive syndrome based on her mood, hopelessness, and a wish to die. She had some equivocal family history of depression, but no previous episodes of depression. The consultant concluded that her depression was a result of several factors—her prolonged hospitalization, the illness and its complications, and the steroids that she was taking. She was prescribed fluoxetine 20 mg per day. She was able to be transferred from the intensive care unit to the general medical service, and she showed some improvement over the next 2 weeks.

But after 2 weeks she refused to take any of her medications, she refused to participate in physical therapy, and she expressed a desire to die. The consultant was called urgently to assess whether she had the capacity to refuse treatment. The patient told the consultant that she was very discouraged, felt abandoned by her family, and felt defeated, as she did not have the energy to cooperate with physical therapy. She just wanted to go home and die. The consultant asked her if she would cooperate with therapy and take medications if she had a bit more energy, so that she could successfully complete a course of physical therapy that will make her strong enough to go home, to which she replied in the affirmative, provided she could sign an advance directive. The consultant decided that the patient did have the capacity to sign an advance directive, and that she should be given a trial of stimulants, which she agreed. She was given methylphenidate 10 mg in the a.m. The next day, she showed remarkable improvement in mood and energy level and was eager to participate in physical therapy. In fact, she was smiling for the first time, and wanted to use the wheelchair. In a week, methylphenidate was discontinued, but she maintained her normalized mood and energy level. She was discharged in 2 weeks, still on fluoxetine, to be followed by an outpatient psychiatrist.

DSM-5 definition includes five or more of Criteria A symptoms during the same 2 week period, which represent a change from previous functioning, and must include either depressed mood or loss of interest or pleasure. They are: depressed mood most of the day, markedly diminished interest or pleasure in activities nearly every day, change in appetite and/or weight, persistent insomnia/hypersomnia, psychomotor agitation or retardation, fatigue or loss of energy nearly every day, feelings of worthlessness or inappropriate or excessive guilt, difficulty with concentration or indecisiveness nearly every day, recurrent thoughts of death or suicidal ideation, plan, or attempt. In addition, Criterion B requires that the symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. Criterion C specifies that the episode is not attributable to substances or other medical condition.

Just as sadness and grief are experienced by most people from time to time, the opposite, pleasurable moods of euphoria and elation, short of mania or hypomania, fall within the normal range of mood. In euphoria, there is a positive feeling of emotional and physical well-being. In elation, there is a definite feeling of joy with increase in self-confidence, motor activity, and energy level. These states can be induced by drugs such as alcohol, narcotics, and amphetamines.

Mania and hypomania, like the depressive syndrome, form a syndrome with definite features and signs. The characteristic feature of the manic syndrome is a distinct period when the predominant mood is elevated, expansive, or irritable and is associated with other symptoms of the manic syndrome. They include hyperactivity, excessive involvement in indiscreet and foolish activities without recognition of the high potential for painful consequences, pressure of speech, flight of ideas, inflated self-esteem, decreased need for sleep, and distractibility. The patient may describe the elevated mood as being euphoric, unusually good, or high. The good mood may have an infectious quality, so that the physician and others in contact with the patient may find themselves feeling expansive and elated. The patient may show indiscriminate enthusiasm in relating to people or in planning things, so that they may start a dozen projects at once, call up distant relatives and acquaintances all over the globe, and go on a buying spree.

On the other hand, the mood may be characterized by irritability rather than joyfulness, especially when the patient’s expansiveness is thwarted. The patient then becomes touchy and domineering. The hyperactivity is often generalized, including participation in multiple activities that may be sexual, occupational, political, or religious. The patients often have poor judgment, and the activities are disorganized, flamboyant, and bizarre. Manic speech is usually loud, rapid, and difficult to understand. It is often full of jokes and puns and is theatrical, with singing and rhetorical mannerisms. In the irritable mood, there may be hostile comments and angry outbursts. Abrupt changes from topic to topic based on understandable associations and distracting stimuli often occur (flight of ideas). When severe, the speech may be incoherent. Distractibility is usually present.

Self-esteem is usually inflated, with unrealistic and uncritical self-confidence and grandiosity. For example, the patient may give advice on matters about which he or she has no knowledge whatsoever, such as how to perform a surgical procedure or how to run the federal government. Grandiose delusions may occur, such as, “I have a special hot line to God.”

Hypomania refers to elevated mood with many of the symptoms of the manic syndrome but not severe enough to interfere with function significantly. If there are psychotic features, the episode is by definition manic (APA 2013).

Evaluation of depression is probably the most common reason for requesting psychiatric consultation (the second most common reason is likely to be delirium).

The depressive syndrome and manic syndrome are final common pathway syndromes with varying degrees of contribution by genetics, early experiences, developmental factors, prescription and recreational drugs, physical illness, and recent and current stresses including hospitalization (see Chap. 7). Once a phenomenological diagnosis of depression or mania/hypomania is made, a differential diagnostic process should be undertaken to determine whether there is prominent contribution by an identifiable physical illness or prescription and recreational drugs, that is, a secondary mood syndrome (see Chap. 4; also see Table 7.​1 in Chap. 7).

Depression is commonly comorbid with many medical conditions including heart disease, stroke, seizure disorder, lung diseases such as asthma and COPD, cancer, HIV, liver disease, kidney disease, as well as in peripartum states, etc. Specific discussions of depression in these conditions are found in chapters dealing with these conditions.